With the development of radio communication and network technologies, technologies for constructing a radio base station in a distributed form have been recently proposed.
The technologies for constructing a radio base station in a distributed form are based on a scheme in which a digital unit (DU) configured to process digital signals and a radio unit (RU) disposed at a remote location are separated from each other, the DU is installed in a data center and the RU is installed in a remote target service area, the DU and the RU are connected to each other, and then data is transmitted and received.
Korean Patent Application Publication No. 10-2013-0051873 relates to “a Radio Base Station and a Data Processing Method therefor,” and discloses the radio base station including: a group DU configured to include a plurality of digital units (DUs); and a plurality of Remote Radio Frequency Units (RRUs) connected to the group DU over a transport network and installed in respective target service areas; wherein each of the DUs includes a MAC function unit configured to perform a transmission/reception Medium Access Control (MAC) function, and each of the RRUs includes an encoder configured to encode downlink data received from each of the DUs. According to this technology, a plurality of DUs is grouped, a radio unit (RU) is connected by an optical cable over a transport network, and then data is processed, thereby providing the effect of reducing the amount of data that is transmitted and received.
However, the transport network is constructed using an optical cable and a coaxial cable via separate switching units, and thus this technology has limitations in that a system cannot be constructed using existing commercial IP network equipment or Ethernet network equipment at low cost and in that flexible multi-layer RU grouping and efficient interworking among a plurality of DUs and multi-layer RU groups cannot be performed using the multicasting/broadcasting function of an IP network or an Ethernet network.